Wireless communication systems commonly include information carrying modulated carrier signals that are wirelessly transmitted from a transmission source (for example, a base transceiver station) to one or more subscribers (for example, subscriber units) within an area or region.
FIG. 1 shows a portion of a single cell of a cellular wireless network system. A base transceiver station 110 provides a wireless connection to a plurality of subscriber units 120, 130, 140. The base transceiver station is generally connected to a network that provides access to the Internet. The cell of FIG. 1 is generally repeated forming a cellular network. The base transceiver station 1 10 and the subscriber units 120, 130, 140 include one or more antennas allowing two-way communication between the base transceiver station 110 and the subscriber units 120, 130, 140.
Generally, information is transmitted between the base transceiver station 110 and the subscriber units 120, 130, 140 in packets or units of data. Typically, a schedule or map must be generated that determines when the units of data are transmitted between base transceiver station 110 and subscriber units 120, 130, 140. The bandwidth of the available transmission frequencies is limited. Therefore, the transmission between multiple transceiver stations and subscriber units generally requires time, frequency, or some other type of multiplexing. The larger the number of base station transceivers and subscriber units, the more complex the scheduling or mapping.
The transmission can be time division duplex (TDD). That is, the down link transmission (transmission from the base transceiver station to a subscriber unit) can occupy the same channel (same transmission frequency) as the up link transmission (transmission from a subscriber unit to the base transceiver station), but occur at different times. Alternatively, the transmission can be frequency division duplex (FDD). That is, the down link transmission can be at a different frequency than the up link transmission. FDD allows down link transmission and up link transmission to occur simultaneously.
Generally, wireless systems are not as reliable as wired system. As a result, data being transferred between a base transceiver station and a subscriber can be miscommunicated or lost. This condition makes the scheduling difficult, because of difficulties in determining whether data must be rescheduled and retransmitted due to being lost. Tracking the amount of data to be transferred at both the base transceiver station and at the subscriber unit aids in the management of the wireless transmission of data between the base transceiver station and the subscriber unit.
Generally, a subscriber unit must indicate to the base transceiver station that the subscriber unit has data to be transmitted to the base transceiver station. This can be accomplished by the subscriber unit transmitting a Request to Send (RTS) signal to the base transceiver station when the subscriber unit has data to transmit to the base transceiver station. It is possible for more than one subscriber unit to transmit an RTS signal at the same time, causing RTS signals to never be received by the base transceiver station. Therefore, most wireless systems include contention management to account for simultaneous RTS transmissions. Contention management can include re-sending RTS signal according to some predetermined pattern. The fact that RTS signals typically have to be transmitted multiple time in order to be successfully received, reduces the efficiency of a wireless system.
It is desirable to have an apparatus and method that provides scheduling and management of the transmission of data blocks between a base station transceiver and at least one subscribers unit. It is desirable that the scheduling be able to successfully manage data blocks that are lost while in transmission, minimize the number of RTS signals transmitted, and minimize the management of the transmission scheduling. Additionally, it is desirable that the data block transmission be adaptive to the quality of transmission links between the base station transceiver antennas and each of the subscribers (subscriber) units.